Hard of course to exactly place when proto-language began but "nothing like" is very clearly an overstatement. Most who I've read think that the major changes from early proto-language to language were not in brain structure but in how that structure was used. Most think language developed in anatomically modern humans. In that sense college students are not so different than humans a hundred thousand or so years ago.

And the point of the study was not "need to" but using gesture in even an ad hoc primitive proto-language fashion does so much more efficiently than just watching and imitating. A group that could do that would be able to make tools better, more reliably, and more of them, than one that relied on imitating alone. The behavior would be thus strongly selected for. "Advanced language" did not emerge fully formed. The hypothesis suggests that cognitive skills and manual skills needed to execute the "lego snap-together nature of compound tools" were applied as tool to more effectively and efficiently teach the skills to others, and that application to cultural transmission, communication, and teaching each other was also then more broadly applied to communicating about concepts other than tool making and provided the cognitive substrate for more advanced language to develop.

Clearly it is not the only hypothesis out there but it is true that current anatomically modern humans transmit tool making knowledge much more effectively using even just ad hoc gestures than by imitation alone and that the brain areas involved in language have great overlaps with those involved in tool use, and that mirror neurons are involved in both. Those facts seem to me to provide solid support for the hypothesis.

Wasn't this a farming thread?

But farming starts with tools... and passing on wisdom.

Another point is - that the tool-making human had to recognize the other wanted to see what they were doing, and needed to understand that they needed to show what the steps were, and needed to conceptual ability to realize that showing a fellow tribe member (offspring?) how to make their own was a good thing and they should do it. Which leads to more abstract knowledge that needs to be passed on, like the best season to plant... How to tell which rocks are good for making knives, etc.